Modern computer and communication networks are capable of supporting calls to and from a variety of network user equipment. The network user equipment may utilize many different protocols, classes and options (PC&O) as part of their normal operation. There are several protocol possibilities, each with its own set of classes and options, which may exist at a time for any given piece of user equipment attached to the network. To provide optimal network service across all PC&O variations, the network therefore supports a variety of packet, frame, cell, and/or circuit based user information transport methods internal to the network.
To determine which PC&O to use, calling and called network users "negotiate" between themselves and the network, at call establishment time, in a three-party exchange. The PC&O provides the network with enough information during call negotiation to select the appropriate method for user information transport. The network negotiation should be accomplished without unduly constraining any user-to-user negotiation taking place over and above that occuring internal to the network during call establishment.
Several problems are attendant in this process. The mismatch of PC&O between calling and called users create a problem for network implementation. Frequently, the network is not made aware of a user's PC&O requirements until the user requests a call from the network. Similarly, the network may be unaware of the called user's PC&O requirements until after the called user responds to a network notification of an incoming call. The network must consolidate and harmonize the potential PC&O differences to determine the appropriate method for user information transport to be used in support of the call. Furthermore, the PC&O requirements of the calling user may combine with PC&O requirements of the called. user so as to affect the resources which must be allocated to the call to support the method of user information transport.
Present computer network provide single methods of user information transport. In Present negotiation strategies require that the network negotiate between calling and called users in a singly circular fashion, passing PC&O from the calling user (source) to the called user(s) (destination(s)) and return. As the network does not aquire PC&O from both the source and destination(s), the method of user information transfer by the network is not optimized for the finally negotiated PC&O. Calls are implemented in present compute networks simply by applying user information transport methods which may vary only in protocol options and not by protocol and class.
In addition, if PC&O information is known prior to the user's call, then the information for the calling user and the called user must be stored for use by the network. If the PC&O information is stored, whenever a user changes equipment, the stored information about the PC&O must be changed.
If PC&O information could be obtained at call time while still conducting the negotiation effectively, the network could select a method of user information transport optimal for the negotiated user PC&O. Also, obtaining PC&O at call time results in greater flexibility in network operation and maintenance, since user equipment could change while requiring minimal changes configuration information.